Pulm Flashcards
What’s the earliest a pre-mature baby can survive?
25-26 weeks. By this point, the alveoli have developed so gas exchange (breathing) is possible.
What does atalectasis mean?
Collapsing of the alveoli
What is aspiration?
When food or vomit gets into the airways
What’s more anterior- the trachea or the esophagus?
The trachea
What are causes (3) of hypercapnia?
Hypercapnia= high CO2 in the blood. Causes:
- Fever (increased metabolic activity)
- Hypoventilation (blowing off less CO2)
- Dead space (ventilation w/o perfusion. There is a blood flow problem, so CO2 is remaining in the blood rather than getting pushed into alveoli)
Does shunting (perfusion w/o ventilation) lead to hypercapnia (inc CO2)? Explain.
No. You have a ventilation problem but blood will shunt to the alveoli that are working and shunted away from the alveoli that are not working/ not ventilating/ not capable of gas exchange. So CO2 will not build up. *you will get inc CO2 in the case of dead space where you have a blood flow problem that prevents the CO2 in blood from getting pushed up into the alveoli
What is dyspnea?
Shortness of breath (SOB)
When does lung development begin in embryo?
Week 4
What structure do the lungs develop from in embryo?
The lung bud (“respiratory diverticulum”)= outgrowth of the GI tract (specifically the foregut, or future esophagus)
Explain the main events in each stage of lung development: (1) embryonic (weeks 4-7), (2) pseudoglandular (weeks 5-17), (3) canalicular (weeks 16-25), (4) saccular (week 26-birth), and (5) alveolar (week 36-8 years).
(1) embryonic (weeks 4-7): lung bud branches down to tertiary bronchi
(2) pseudoglandular (weeks 5-17): there’s branching all the way down to terminal bronchioles (lungs resemble a gland)
(3) canalicular (weeks 16-25): terminal bronchioles further branch into respiratory bronchioles and alveoli w/ lots of capillaries. Pneumocytes develop at 20 weeks (type II pneumocytes make surfactant).
(4) saccular (week 26-birth): alveoli further develop and form sacs (seperated by septae)
(5) alveolar (week 36-8 years): “alverolarization” (alveoli get subdivided by septa walls so that they are smaller but there’s triple the amount—> inc surface area)
What is oligohydramnios? Why is this a problem for lung development?
Decreased amniotic fluid (from fetal kidney problem—> dec urine= dec amniotic fluid production) (part of Potter sequence). The baby in embryo needs to swallow amniotic fluid to expand their developing lungs. Amniotic fluid fills baby’s lungs and stimulates further development of the lungs. W/o enough amniotic fluid, the baby is born with PULMONARY HYPOPLASIA= underdeveloped lungs.
What is pulmonary hypoplasia?
Underdeveloped lungs. Associated with congenital diaphragmatic hernia (pleuroperitoneal membrane not formed properly—> hole in diaphragm—> abdominal organs herniate into chest and prevent proper lung development) and bilateral renal agenesis (fetal kidney problem—> lack of urine= lack of amniotic fluid—> lungs aren’t stimulated to develop fully)
What are bronchogenic cysts?
Abnormal budding of the foregut and dilation of terminal/ large bronchi. Cysts are fluid filled, lined by respiratory epithelium, contain cartilage
What is bronchopulnoary dysplasia?
Lung disease that affects premature babies. Caused by damage from mechanical ventilation (O2 toxicity, lung trauma)—> alveolarization (alveoli subdividing so you have more, smaller alveoli= inc SA) doesn’t progress normally—> respiratory problems during infancy (but often improves in childhood as lungs continue to develop).
What are club cells?
Non-ciliated cells in bronchioles (beginning of respiratory zone). Secrete a component of surfactant and do detoxification.
Describe type I and type II pneumocytes (alveoli cells).
TYPE I: makes up 97% of your alveolar cells. Line the alveoli. Squamous and thin for optimal gas exchange.
TYPE II: secrete surfactant to dec surface tension and prevent alveolar collapse. Cuboidal. Also can proliferate into other cells during lung damage to help heal the lungs.
What ingredients is surfactant made of?
Lecithins. The most important one is DPPC (dipalmitoylphosphatidylocholine)
During what week of development does surfactant start getting made?
Week 26
What is neonatal respiratory distress syndrome (NRDS)? What are 3 risk factors?
Surfactant deficiency (breathing disorder from immature lungs). Risk factors: premature baby, maternal diabetes (insulin dec surfactant production) C-section delivery (cortisol inc surfactant production and C-sections= less stressful delivery= less cortisol= less surfactant production).
What test can we do to screen for fetal lung maturity?
Lecithin-sphingomyelin. Lecithin (what surfactant is made of) should shoot up late in pregnancy when the baby lungs mature. A ratio of >2 is healthy. If <1.5 that’s predictive of NRDS (neonatal respiratory distress syndrome= surfactant deficiency= baby born with immature lungs and will need help breathing for a while)
Starting with the trachea, name all the respiratory tract anatomical structures in order.
Trachea—> primary bronchus—> secondary bronchus—> tertiary bronchus—> bronchioles—> terminal bronchioles (end of conducting zone)—> (start of respiratory zone) respiratory bronchioles—> alveoli
What is the general purpose of the conducting zone? Respiratory zone?
Conducting zone: warms, humidifies, and filters air. Respiratory zone: does gas exchange.
What kind of cells secrete mucous as a way of protecting against infection?
Goblet cells in the bronchi.
How many lobes make up the right lung? Left lung?
Right lung: 3 (upper lobe, middle lobe, lower lobe)
Left lung: 2 (upper lobe and lower lobe) heart on this side!